The invention relates generally to sports shoes or boots such as football boots or the like, and more particularly to the sole for such a boot or shoe. For the sake of simplicity herein the term sports shoe will be used to cover any appropriate form of sports shoe, sports boot (being generally of a heavier construction than a sports shoe in the narrow sense) and the like.
Sports shoes are known, the soles of which have a plurality of ground-engaging or gripping portions or elements, for example up to around twenty thereof, being predominantly formed integrally with the sole. Because of the material used for forming the gripping elements or studs, they have a certain degree of resiliency and flexibility. Such soles are preferably used by sportsmen when the resilient deformability of the projections or studs formed by the gripping elements, which contrasts with the replaceable kind of stud which is usually hard, and the damping or shock-absorbing effect which results from such resiliency of the projections, is to be utilised. That applies in particular in regard to hard grounds and playing areas which nonetheless still require the use of gripping projections or studs in order to ensure a satisfactory grip when playing a game. In addition, sports shoes with soles having integral projections or studs of the above-indicated kind are also extensively used by footballers when training as they have been found for example to cause less injury.
A long-standing problem in regard to such sports shoe soles is that, once the gripping projections or studs are worn, the entire sole and thus the entire shoe can no longer be used, even if the upper portion of the shoe is still in satisfactory condition. In order to increase the service life of the sole of the shoe, so that it is at least approximately equivalent to that of the shoe in its entirety, the sole must be made from a plastic material which has a very high degree of resistance to wear. As that causes the cost of the sole to be increased, it has been suggested that the projections alone may be made from a wear-resistant material, and joined to the sole, which thus comprises a cheaper material, in the sole casting or moulding operation. However, that suffers from the disadvantage that the harder material of the projections or studs considerably reduces the degree of resiliency and damping effect which is precisely required of such studs or projections. Basically, that consideration also applies in regard to projection-bearing soles for sports shoes, wherein the projections or studs are formed by cap members of wear-resistant material which can be secured by screwing to securing projections or fitments on the sole, having a male screwthread for securing the cap in position (see French patent specification No. 2 070 253). However, a disadvantage in such an arrangement is that the fixing fitments often suffer irrepairable damage if the person using the sports shoes does not replace the caps in good time, before at least the ground-engaging part of the projection caps is completely worn out.